Skip the auto shop - Our mechanics make house calls

Q: Engine puffs blue smoke; thumping noise at highway speeds

asked by on

In the mornings when I start my SUV, for a few seconds the engine puffs blue smoke. When I’m driving on the highway at 60 mph, it begins to make a very obnoxious thumping sound that can also be felt by the vibrations. It feels like there is something stuck to the tire, but when I examine them, I don’t find anything. With more speed, the louder it becomes. I have looked at the transmission, driveline, shafts - all seem fine. Another problem is that when I am braking, the steering wheel shakes and there is a loud noise under the brake pedal. I have already changed the brake pads and the rotors, machined them, etc. No repairs have worked! I would greatly appreciate your advice on what will fix my car. Thanks.

Hi there, thanks for asking about your 2004 Infiniti FX45. The blue smoke you notice on initial start-up is likely caused by worn exhaust valve stem seals. They allow a tiny amount of oil to get into the combustion chamber while the car sits overnight. This will slowly get worse with additional miles until the valve stem seals are replaced. Have the front tires and wheels checked for balance, "roundness", or any separation of the tread of the tire at a reputable tire dealer. There is likely something amiss that’s showing up at highway speed and under braking. If you want to have this checked by a certified mechanic, a technician from YourMechanic can come to your home or office to inspect the smoke coming from your car’s exhaust.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Right front disc brake seizing

It is possible that the newly installed caliper was faulty. It is also possible that the wheel bearing on the right front wheel is completely destroyed and no longer able to rotate. This issue may also cause an ABS or...

Q: Car won't run after running rough

Hello, from your description it sounds like you might have fuel injector that is stuck open. A stuck open fuel injector will let fuel just flow into a particular cylinder, letting raw fuel just go strait into the exhaust without...

Q: Should I be able to spin front wheel by hand while other wheel is on the ground

Hey there, thanks for writing in about your 2002 Jeep Grand Cherokee. Make sure that you are not in four-wheel drive mode. Sometimes when the hubs lock, they make a clunking noise and the whining noise could be a gear...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...